Evolution, variation, biodiversity, classification Flashcards
Which two factors can cause variation in the phenotype?
Genotype and environment
What is continuous variation?
Variation that shows a gradation from one extreme to another. Often affected by more than one gene in combination with the environment
What is discontinuous variation?
Characteristics that are clear cut and easy to tell apart with no intermediates. Eg blood group. Controlled by different alleles of one gene with no effect from environment
Variation that is passed on via the genes is called?
Heritable variation. Otherwise it is non heritable variation
What are interspecific and intraspecific competition?
Intraspecific is between individuals of the same species, interspecific between individuals of different species
Name three ‘selective agents’ that could impact survival of organisms
Supply of food, climate, breeding sites, human impact
What is a gene pool?
All the alleles of all the genes of all the individuals in a population at any one time
Give the steps of natural selection
- Mutation causes variation 2. A change in the environment causes a selective pressure 3. Individuals that have alleles causing them to be better adapted will survive and reproduce 4. Advantageous alleles are passed on 5. Over many generations the advantageous allele becomes more frequent in the population
What are the two Hardy Weinberg Equations and what do the letters stand for?
p+q= 1 (where p is frequency of dominant alleles and q the recessive allele). p^2+q^2+2pq=1 (where p^2 is homozygous dominant, q^2 is homozygous recessive, 2pq are heterozygotes)
What conditions must be true for the Hardy-Weinbert principle to apply?
A large population (so little genetic drift), no selection, mating is random, no mutations, no migration
What is genetic drift?
Random changes in allele frequencies
What is allopatric speciation?
Speciation that is caused by a physical/geographic barrier which prevents interbreeding between two groups
What is sympatric speciation?
Speciation that occurs despite the two groups being in the same location.
What could cause sympatric speciation?
Behavioural mechanisms such as courtship displays, differences in morphology or breeding seasons, hybrids being infertile due to odd number of chromosomes
What is the founder effect?
A new population is established by a small group of individuals from a larger population. The new population will have reduced genetic variation and may not be representative of the original population.
What is a genetic bottleneck?
A reduction in genetic diversity due to a drastic decrease in population size
What is the definition of a species?
A group of organisms that can interbreed to produce fertile offspring
Give the taxa from largest to smallest
Kingdom, phylum, class, order, family, genus, and species.
What is classification?
The organisation of living organisms into groups according to shared characteristics
What is a phylogenetic hierarchy?
When organisms are split into smaller and smaller groups according to evolutionary relatedness
What is the proper term for a diagram that shows how related organisms are in terms of evolutionary history?
Phylogenetic tree/cladogram
How should species names be written?
As a binomial that has the genus and species. Genus capitalised, species lower case. It should be in italics.
Why should species be known by their latin name?
It avoids confusion of local common names and different languages
Why is classification described as tentative?
Classification may change as additional information becomes available
What are the three domains?
Bacteria/Eubacteria, Archaea and Eukarya. Each have unique rRNA
Why are archaea called extremophiles?
They exist in a wide variety of environmental conditions including extremes of temperature, pH, salinity and pressure
What are the five kingdoms?
Prokaryotes, protoctista, plants, fungi, animals
What mechanisms can be used to classify organisms?
Similar morphology or biochemical methods
What are homologous structures? Give an example
Features that evolved from the same original structure but are used for different functions (divergent evolution)- eg the pentadactyl limb in vertebrates
What are analogous structures? Give an example
Features that have the same function but a different evolutionary origin (convergent evolution). Eg the wings of birds and insects
Define biodiversity
The number of species and the number of individuals of each species in a given environment
What do you need to know in order to calculate biodiversity?
Species richness (number of different species present) and species evenness (number of individuals of each species)
When using Simpson’s Diversity Index, what does a value closer to 1 show?
Higher biodiversity
What is polymorphism?
When several versions of a feature are present in the population, due to polymorphic genes- multiple alleles for the same gene. Such as blood groups in humans
What are the three types of adaptation an organism can have to its environment?
Anatomical, behavioural, physiological
What is DNA hybridisation?
Strands of DNA from different species form hydrogen bonds. The temperature at which they separate again shows how many hydrogen bonds they have formed, and hence how similar the DNA sequence is and how closely related the organisms are.
Why is analysing amino acid sequences of proteins useful for taxonomists?
Closely related species have more similar proteins because they have more similar DNA sequences coding for them.
